Latent Acid Catalysts for enhanced Thermoset Process Control

The ability to control the reactivity of a pre-polymer catalyst system is crucial for manufacturing economics when processing thermosetting resins in both pressurised and non-pressurised processes. Such systems are used in hundreds of applications including the manufacture of chipboard and laminates, glass-reinforced plastic composites, and the manufacture of oil filters and abrasives. Bac2’s CSR latent acid catalysts can be added to pre-polymeric resins to enable them to be stored prior to controlled polymerisation, with formulations available to enable the optimum ratio of storage stability (pot-life) and reactivity to be achieved.

The search for an effective latent acid catalyst that can retard an acid catalysed polymerisation reaction for a significant period has been a goal for industrial chemists for many years. Bac2 originally developed a novel latent acid system for use in the production of advanced composite bipolar plates, components for fuel cell applications, using acid cured phenolic and furan polymers. The special feature of the latent catalysts is the use of hydroxylamine as the base in association with a strong acid to give a stable adduct. Unlike all other bases, the hydroxylamine component begins decomposition at 50°C and decomposes completely above 120°C leaving the acid completely free to begin the catalysis.

It is the decomposition of hydroxylamine itself rather than the salt, an action that completely releases the acid to begin the polymerisation, which gives the CSR latent acid catalysts longer-term stability and a significantly lower activation temperature than other latent acids.

Stable compounded formulations can be compression moulded after 12 months storage at room temperature to produce a part of the same dimensions and properties of a moulding produced after only 24 hours.

Bac2 has broadened the use of the catalysts to phenolic and renewable furan based BMC, SMC and pre-pregs for industrial and advanced composites applications.

Blendable CSR 20 and CSR100

CSR20 and CSR100 are liquid, blendable latent catalysts for use with acid polymerisable pre-polymers including phenolic, furan and amino resins. The catalysts contain strong acids. Formulations based on nitric acid and others are available. CSR20 is a reactive form for use with low condensed polymers and is used at low addition levels. CSR100 is a slower reactivity grade for use with pH sensitive resins. The catalysts are offered as a twin pack to allow blending of the liquids to suit the resin reactivity. CSR catalysts are rapidly activated at temperatures above 120°C. Slower activation at temperatures above 50°C is possible. CSR catalysts are water-soluble.

After evaluation of the CSR20 and CSR100 blend catalyst and blends, a single grade customised blend can be supplied.

Blendable CSR150 and CSR250

CSR150 and CSR250 are liquid, blendable latent catalysts tailored specifically for use with amino resins. The catalysts contain higher levels of hydroxylamine than CSR20 and CSR100. In other respects they are similar.

CSR800

CSR800 has been developed as a non-aqueous version of CSR for use in water intolerant systems. CSR800 is potentially available in a range of organic solvents. Contact Bac2 for more information on this.